looks like every part is custom made down to the screws...
I always wondered who deigns the machines that make the parts?

When I asked a repair guy to oil the keybed on PSR-S950 because it started to make too much noise, at first he hesitated but then he agreed and the problem was fixed. But he explained afterwards that the keybed is not actually designed to be disassembled (he had to disassemble it) and doing it few times can brake it at all. I guess, my point is that what we see in this video is a rather mysterious process for most people; it is highly optimized and the sad fact is that the final product is not supposed to last for many years if used intensively, also it’s not supposed to be easily repaired. A pitch bend wheel on my S950 has broken again after it was fixed 6 months ago. I guess, the message is “come on, buy a new arranger”.

As for people who designed and programmed these machines, they are surely brilliant engineers; while we are playing PSRs they deal with different kind of challenges.

The PRO level instruments are well built for heavy use...but the Arrangers are considered home keyboards (but of course are used professionally a lot too)

Anything where self tapping screws are fixed into plastic has a limited number of Disassembly and rd-assembly cycles but with care you can do this a few times. I've had my old PSR3000 apart at least 5 times due to LCD and keyboard issues. There is a specific type of plastic grease you can use to keep the keyboard smooth.

When reassembling take care to find the original screw thread in the hole and preferably hand tighten everything but not too much, you do not want to strip the plastic thread. And always put the same screw back into the hole, When tightening screws remember that if it feels tight straight away you've probably got something wrong. Similarly if the screw gets tight before any gap has fully closed then you've got something stuck in the gap!